Dynamic spectrum partitioning between a first radio access technology and a second radio access technology

ABSTRACT

An eNodeB uses a first portion of a frequency spectrum as a primary cell and uses a second portion of the frequency spectrum as a secondary cell that is dynamically shared with a 5G base station. The eNodeB and the 5G base station communicate to dynamically share the second portion of the frequency spectrum.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/661,079, filed Oct. 23, 2019, which is a continuation of U.S.application Ser. No. 15/062,162, filed Mar. 6, 2016 (now U.S. Pat. No.10,462,675), which are incorporated herein by reference in theirentirety.

FIELD OF THE DISCLOSURE

This disclosure relates to deployment of next generation (5G) cellulartechnology.

BACKGROUND

The next generation telecommunications network, referred to herein as5G, is expected to comprise of two distinct radio access technologies(RATs). A first RAT is sub 6 GHz and a second RAT utilizes mm waves withfrequencies ranging from 30-300 GHz. Of these two RAT components, thesub 6 GHz is expected to be deployed first.

The current generation of radio access technology is defined by variousThird Generation Partnership Project (3GPP) Long Term Evolution (LTE)Specifications. For example, the physical layer (L1) of LTE is definedin various specifications including 3GPP TS 36.211 v9.1.0 (2010-03) 3rdGeneration Partnership Project; Technical Specification Group RadioAccess Network; Evolved Universal Terrestrial Radio Access (E-UTRA);Physical Channels and Modulation (Release 9) (and later releases) and3GPP TS 36.212 V9.4.0 (2011-09) 3rd Generation Partnership Project;Technical Specification Group Radio Access Network; Evolved UniversalTerrestrial Radio Access (E-UTRA); Multiplexing and channel coding(Release 9) (and later releases), and other 3GPP specifications.

During deployment of 5G, LTE (also referred to as 4G) technology willstill be in use. Thus, both 5G and LTE RATs will be operatingconcurrently. Effective deployment of 5G while maintaining LTEoperations is desirable.

SUMMARY

Embodiments described herein allow LTE and 5G channels to reside in thesame part of the spectrum and dynamically share spectrum.

Accordingly, in one embodiment a method is provided for a first radioaccess technology to share spectrum with a second radio accesstechnology. The method includes a first base station utilizing a firstportion of the spectrum as a primary carrier during a first time periodto communicate with first user equipment in a first area, the first basestation using the first radio access technology. The first base stationutilizes a second portion of the spectrum as a secondary carrier duringthe first time period, the secondary carrier being aggregated with thefirst carrier to communicate in the first area. A second base stationutilizes at least some of the second portion of the spectrum during asecond time period to communicate with second user equipment in thefirst area, the second base station using the second radio accesstechnology. The first base station utilizes the first portion of thespectrum as the primary carrier during the second time period but doesnot use the second portion.

In another embodiment, a first base station utilizes a first radioaccess technology to communicate in a first area and uses a firstportion of a frequency spectrum as a primary carrier and a secondportion of the frequency spectrum as a secondary carrier aggregated withthe primary carrier during a first time period. A second base stationutilizes second radio access technology to communicate in the firstarea, the second base station utilizing the second portion of thefrequency spectrum during a second time period. The first base stationis communicatively coupled to the second base station to synchronizedynamic sharing of the second portion of the frequency spectrum duringthe first and second time periods.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood, and its numerousobjects, features, and advantages made apparent to those skilled in theart by referencing the accompanying drawings.

FIG. 1 illustrates the utilization of the sub 6 GHz spectrum for LTE and5G.

FIG. 2A illustrates an area in which a 5G base station and an eNodeBserve user equipment (UE), some of which have 5G capability and some ofwhich have only LTE capability.

FIG. 2B illustrates an overlap area between a 5G cell and an LTE cell.

FIG. 3 illustrates dynamic partitioning of the spectrum between 5G andLTE.

FIG. 4 illustrates how a portion of the 5G primary cell spectrum may beshared with the LTE secondary cell.

FIG. 5A illustrates a flow diagram of the signaling between a 5G basestation and an eNodeB as part of the dynamic partitioning process fromthe perspective of the 5G base station.

FIG. 5B illustrates a flow diagram of the signaling between a 5G basestation and an eNodeB as part of the dynamic partitioning process fromthe perspective of the eNodeB.

FIG. 6A illustrates a block diagram of 5G and LTE transmittersillustrating how spectrum is shared.

FIG. 6B illustrates a high level block diagram of an LTE receiver.

FIG. 6C illustrates a high level block diagram of a 5G receiver.

FIG. 7 illustrates the 5G transceiver when the partitioning gives theLTE SCell spectrum to 5G.

FIG. 8 illustrates an example base station that may be used for 5Gand/or LTE communications.

FIG. 9 illustrates sharing spectrum using duty cycles.

The use of the same reference symbols in different drawings indicatessimilar or identical items.

DETAILED DESCRIPTION

It is currently believed that substantial spectrum will not be allocatedin the United States for deployment of the sub 6 GHz component of 5G.Therefore it is very likely that in the early 5G deployment, both 5G andLTE will be deployed in the same band.

From past experience, clearing spectrum for deploying a new generationof technology requires the network be made more dense. The need to clearspectrum is unnecessary if new spectrum is available for the new RATgeneration, but as stated previously this is unlikely to be the case forthe sub 6 GHz 5G deployment.

In order to deploy 5G technology, wireless carriers need to carve out 20MHz or more of spectrum. Not only is that expensive but when the 5Gcarrier is deployed, the 5G spectrum remains underutilized for a periodof time as 5G utilization ramps up. Accordingly, it is desirable toensure a smooth upgrade path from LTE to 5G, which requires both the LTERAT and the 5G RAT to be able to operate in the same spectrum as shownin FIG. 1. The sharing in FIG. 1 shows that prior to 5G deployment at101, the entire spectrum is allocated to LTE. At 103, the spectrum isshared by 5G and LTE. Eventually, when LTE support ends, the entirespectrum is allocated to 5G as shown at 105.

Partitioning the spectrum as shown in FIG. 1 statically, usually leadsto loss in efficiency. Because utilization of 5G is small at initialdeployment, spectrum allocated to 5G will not be heavily utilized.Similarly, when 5G has significantly penetrated the market and LTE usagehas declined, spectrum allocated to LTE becomes underutilized. Whileperiodic reallocation of static spectrum may help alleviate theinefficiency, greater efficiencies can be achieved by requiring that thepartitioning between 5G and LTE be dynamic and allowing 5G and LTEchannels to reside in the same part of the spectrum. By allowing thespectrum partitioning between 5G and LTE to be completely dynamic,depending on the volume of traffic on LTE and 5G channels, the LTE and5G channels can be adjusted in frequency and time. Spectrum that is notused by LTE can be dynamically used by 5G and spectrum not used by 5Gcan be dynamically used by LTE. The dynamic allocation can be achievedover very small time scales such as tens of milliseconds. Thus, althoughthe allocation between 5G and LTE may not change on a per transitiontime interval (TTI) basis, techniques described herein allow dynamicallocation over fairly short time scales (e.g., tens of milliseconds)using the secondary cell (SCell) activation/de-activation on the LTEcarrier. The short time scales of the dynamic partitioning makes iteasier and more cost effective to deploy 5G and also allows efficientuse of the spectrum resources when 5G technology is deployed andunderutilized in the initial deployment phase. In other embodiments, asdescribed further herein rather than being completely dynamic, thespectrum may be shared on a more static basis.

Secondary cell activation/deactivation is a mechanism provided in LTE toachieve carrier aggregation where contiguous or noncontiguous carrierspectrum is added to the primary cell carrier spectrum to achieve higherthroughput. For example, the LTE primary cell spectrum may provide 5,10, 15, or 20 MHz of bandwidth and the secondary cell primary cellspectrum may provide another 5, 10, 15, or 20 MHz.

FIG. 2A shows an example area 200 being utilized by both 5G and LTERATs. Note that the area is shown as completely overlapping for the tworadio access technologies. The area 200 includes an LTE base station(eNodeB) 201 and a 5G base station 202. The user equipment 203 ₁ and 203₄ are 5G UEs, while the UEs 203 ₂ and 203 ₃ are LTE devices. Thus, for asub 6 GHz deployment of 5G, the spectrum in area 200 can be shared by 5Gand LTE. A communication interface 205 between enodeB 201 and the 5Gbase station 202 allows synchronization between the eNodeB and the 5Gbase station to achieve dynamic partitioning of the spectrum asdescribed further herein. Note that although the 5G base station andeNodeB are shown separately, in embodiments they may be collocated andthere may be substantial overlap between the 5G base station and theeNodeB. FIG. 2B shows an embodiment having a partial overlap 250 betweenthe LTE cell 251 and the 5G cell 253.

Co-existence and dynamic partitioning of LTE and 5G in a frequencydivision duplex (FDD) and time division duplex (TDD) spectrum can beachieved, e.g., for the case when the LTE carrier (or carriers) to beshared has a bandwidth of W and the 5G carrier (or carriers) has abandwidth of W+□W (see FIG. 1). W can be, but is not limited to 5 MHz,10 MHz, 15 MHz and 20 MHz. □W is the additional bandwidth spanned by the5G carrier. There may be a lower limit to □W, which is the minimum 5Gchannel size. Note that FIG. 1 is not to scale. The 5G and LTE RATtechnologies differ. For example, LTE utilizes orthogonal frequencydivision multiple access/single carrier frequency division multipleaccess (OFDMA/SCFDMA) for the downlink/uplink. In contrast, the physicallayer (L1) of the 5G RAT is expected to use a filtered multicarrierapproach, e.g., filtered OFDM, Unified Filtered Multi-Carrier (UFMC), orFilter Bank Multicarrier (FBMC).

FIG. 3 illustrates an embodiment of the dynamic partitioning between LTEand 5G. LTE provides for a technique known as carrier aggregation inwhich a primary cell (e.g., primary spectrum 302) may be combined withthe SCell (e.g., secondary spectrum 304) to provide greater LTEbandwidth. The primary cell provides the control plane while thesecondary cell is utilized as a data plane. The additional spectrum maybe contiguous or noncontiguous with the primary cell spectrum. FIG. 3shows an example where the SCell is non contiguous. The LTE carrier tobe dynamically shared is configured as a secondary cell (SCell) for allthe user equipment (UE) for LTE.

In order to provide dynamic sharing of spectrum between 4G and 5G RATs,two components help enable dynamic sharing. One component is secondarycell activation/deactivation to turn on and off the LTE secondarycarrier. In addition, as described further herein, an interface (see 205in FIG. 2B) is provided between the eNodeB and 5G base stations tocoordinate the dynamic allocation of the secondary cell spectrum. Thespectrum allocated to the LTE SCell may be turned on and off as rapidlyas 10-20 msec. Turning of the SCell dynamically can be done with currentLTE capability.

In one or more embodiments the 5G RAT can dynamically turn offsubcarriers even on the 5G primary cell (PCell). That feature can beuseful since even though the LTE carrier is an SCell, some of thespectrum allocated to the LTE SCell may be spectrum allocated to a 5Gprimary cell. Referring to FIG. 4, assume when the entire spectrum 400shown is allocated to a 5G PCell, the 5G control plane resides in thespectrum portion 401. The 5G UE measures the entire spectrum 403 for,e.g., channel state information (CSI) measurement, Radio ResourceManagement (RRM) or Radio link Monitoring (RLM) measurements. However, aportion 404 of the PCell (but not the control plane) may be turned offand allocated to the LTE SCell. The 5G UE are able to handle the dynamicturning on/off the subcarriers (those that overlap with the LTE carrier)without the dynamic turning on/off affecting any measurement procedurefor, e.g. channel state information (CSI) measurement, Radio ResourceManagement (RRM) or Radio link Monitoring (RLM) measurements. Thesub-carriers being turned on and off can be handled blindly by the UE orcan be explicitly signaled by the 5G network to the UE. That is, the UEcan handle the turn/on and off by assuming that absence of the pilotsignal on a portion of the spectrum indicates no measurement proceduresshould be performed on that portion of the spectrum. Thus, if the UE wasdetecting pilot signals in the spectrum region 404, the UE can concludebased on the later absence of such pilot signals detected by the UE,that the UE should not perform measurement procedures in the portion ofthe spectrum but only in the region 405 where pilot tones are detectedby the UE. The UE may continue to look for pilot tones on a periodicbasis to know when to resume measurement procedures on that portion ofthe spectrum that was turned off. In other embodiments, the 5G networkexplicitly signals the UEs regarding the turning on/off of the spectrumregion 404. Note that only connected devices care about measurements. Ifthe 5G UEs are in idle mode, such measurements typically are not needed.

FIGS. 3, 5A, and 5B illustrate dynamic sharing of the LTE SCell spectrumwith 5G. Such dynamic sharing requires synchronization between the LTEeNodeB and the 5G base station. Referring to FIG. 3, at time 301, theLTE RAT utilizes the LTE PCell 302 and SCell 304. In addition, the 5Gspectrum 306 and 308, which can include PCells and SCells, are operatingat the same time in different portions of the spectrum. When the 5G basestation needs additional spectrum, e.g., for a burst transmission to oneor more 5G UE, the 5G base station utilizes the entire spectrum 310shown at 303 once the LTE eNodeB deactivates the SCell by ensuring thatno transmissions occur by the eNodeB or any LTE UE in that portion ofthe spectrum. Note that the spectrum 310 is shown as a single carrierbut in embodiments may include one or more carriers. Similarly, any ofthe carriers 302, 304, 306, and 308 may be one or more carriers. Oncethe burst is complete, the portion of the spectrum 304 can revert backto LTE use as shown at 305.

FIG. 5A illustrates aspects of the synchronization between the 5G basestation and the eNodeB from the perspective of the 5G base station. The5G base station notifies the eNodeB in 501 of the need for spectrum overan interface between LTE eNodeB and 5G base station such as interface205 shown in FIG. 2A. The interface can be similar to the X2 interfacedefined for communication between eNodeBs in LTE or can be anotherinterface. The 5G base station waits for an indication in 503 from theeNodeB that the LTE SCell has been (or will be deactivated) and the LTESCell spectrum will be available after a delay, e.g., a predeterminednumber of milliseconds after the message is received. When the LTE SCellis de-activated then the 5G base station can start using sub-carriers inthe SCell spectrum. After the message from the eNodeB is received, the5G base station transmits at 505 5G data shown, e.g., at 303 in FIG. 3utilizing the spectrum previously occupied by the LTE SCell. After the5G transmission is complete, the 5G base station notifies the eNodeB in507 that the 5G transmission is complete (or will be complete after apredetermined time period) and turns off the 5G subcarriers in theportion of the spectrum utilized by the LTE SCell. The eNodeB can thenresume utilization of the SCell spectrum as shown in 305 (FIG. 3).

The transitions between 301, 303, and 305 can be as fast as tens ofmilliseconds. In other embodiments, for example, as LTE utilizationdeclines, the LTE RAT may request use of the LTE SCell when demand issufficiently high and otherwise allow the 5G RAT to utilize the LTESCell spectrum. When the LTE SCell is activated the 5G carrier needs tostop using that spectrum prior to activation. Note that the spectrum302, 304, 306, 308, and 310 may be used for downlink and/or uplinkcommunications.

FIG. 5B illustrates the synchronization from the perspective of theeNodeB. At 521 the LTE is transmitting using the SCell spectrum. In 523,the eNodeB receives a request from the 5G base station to deactivate theSCell. The eNodeB deactivates the SCell and notifies the 5G base stationin 525. The eNodeB then continues utilization of the LTE primary cell(PCell) for LTE communications while waiting in 527 for an indicationfrom the 5G base station that the SCell spectrum is again available forLTE use. When the indication is received, the LTE resumes use of theSCell in 529. Note that the UEs are notified by the eNodeB of theactivation and deactivation of the SCell. Similarly, the 5G devices arenotified about the use of the SCell spectrum for 5G communications, orthe turn on/off may be handled blindly by the UE as described earlier.

FIG. 6A shows high level block diagrams of the LTE transmitter 601 andthe 5G transmitter 603 illustrating how the transmitters can co-exist.Even though logically the LTE eNodeB and the 5G base station areseparate logical entities, in some embodiments the LTE eNodeB and 5Gbase stations may be implemented using a substantial portion of the samehardware. For simplicity, only a portion of the LTE transmitter for theSCell 304 (see FIG. 3) is illustrated. The subcarriers 607 areassociated with the LTE SCell 304 (see FIG. 3). The 5G subcarriers 609and 611 correspond to the portion of the spectrum 306 and 308 allocatedto 5G. As shown in FIG. 6A, the LTE transmitter includes an inverse FastFourier Transform and parallel to serial conversion block 621, a cyclicprefix insert block 623, and a block 625 to convert the signal to RF fortransmission in the LTE spectrum 304. The 5G transmitter includes theiFFT blocks 631, filter 633, which are combined in 637 and converted to5G RF in block 639 for transmission over the 5G spectrum 306 and 308.

FIGS. 6B and 6C illustrate embodiments of receivers for LTE and 5G UEreceivers. FIG. 6B illustrates a conventional LTE receiver 651 thatremoves the cyclic prefix in 653, performs an FFT and serial to parallel(S/P) conversion in 655, performs de-mapping in 656, forward errorcorrection (FEC) decoding in 656, and parallel to serial (P/S)conversion in 658, and detection in 659. From a high level block diagramperspective, the 5G receiver 661 is similar but includes the filter 663corresponding to the filter 633 in the transmitter.

When 5G utilizes the LTE SCell spectrum, as shown in FIG. 7, the 5Gtransmitter utilizes the transmitter portion 701, which is combined withthe transmitter portions 603 to utilize the entire spectrum 310 for 5Gtransmission.

LTE requirements necessitate a conventional guard band between the 5Gportion of the spectrum and the LTE portion of the spectrum.

The ability to partition spectrum over such short time scales allowsfulfillment of the 5G user experience without requiring very largeswaths of spectrum cleared for initial deployment. Such an approachprovides possibly multi-billion dollars of savings during the 5G rollout since new spectrum does not have to be carved out. Dynamicpartitioning of spectrum allows efficient usage of the newly deployedtechnology even when it is underutilized in the initial phase.

To provide further context for various aspects of the subjectspecification, FIG. 8 provides a high level block diagram of an exampleembodiment 800 of a LTE eNodeB or 5G base station that may be used toimplement the dynamic partitioning described herein. As previouslymentioned, a substantial amount of hardware shown in FIG. 8 may beutilized for both the LTE eNodeB and the 5G base station. Forsimplicity, FIG. 8 will be described simply as a base station with theunderstanding that the high level blocks implemented may be utilized byeither the 5G base station of an LTE eNodeB in various embodimentsdescribed herein. In one aspect, the base station 800 can receive andtransmit signal(s) (e.g., data traffic and control signals) to and fromuser equipment, through a set of antennas 809 ₁-809 _(N), for example,utilizing the spectrum shown in FIG. 3. Antennas 809 ₁-809 _(N) formpart of communication platform 825, which includes electronic componentsand associated circuitry for processing received signal(s) (data andcontrol) and for processing signals (data and control) to betransmitted. Communication platform 825 can include atransmitter/receiver (e.g., a transceiver) 866 that can convertsignal(s) from analog format to digital format upon reception, and fromdigital format to analog format for transmission. In addition,transceiver 866 can divide a single data stream into multiple, paralleldata streams, or perform the reciprocal operation. Coupled totransceiver 866 is a multiplexer/demultiplexer 867 that facilitatesmanipulation of signals in the time and/or frequency domain.Multiplexer/demultiplexer 867 can multiplex information (data/trafficand control/signaling) according to various multiplexing schemes such astime division multiplexing (TDM), frequency division multiplexing (FDM),orthogonal frequency division multiplexing (OFDM), filtered OFDM, etc.In addition, multiplexer/demultiplexer component 867 can scramble andspread information (e.g., codes) according to substantially any codeknown in the art. A modulator/demodulator 868 is also a part ofcommunication platform 825, and can modulate information according tomultiple modulation techniques, e.g., M-ary quadrature amplitudemodulation (QAM), with M a positive integer), phase-shift keying (PSK),and the like. The communication platform 825 may include the LTEtransmitter 601 and/or the 5G transmitter including portions 603 and 701(see FIGS. 6A and 7)

Base station 800 also includes one or more processors 845 configured toconfer functionality, at least partially, to substantially anyelectronic component in the base station 800, in accordance with aspectsof the subject disclosure. In particular, processor 845 can facilitateimplementing configuration instructions, which can include storing datain memory 855. In addition, processor 845 can facilitate processing data(e.g., symbols, bits, or chips, etc.) for multiplexing/demultiplexing,such as effecting direct and inverse fast Fourier transforms, selectionof modulation rates, selection of data packet formats, inter-packettimes, etc. Moreover, processor 845 can manipulate antennas 809 ₁-809_(N) to facilitate beamforming or selective radiation pattern formation,which can benefit specific locations covered by the base station 800;and exploit substantially any other advantages associated withsmart-antenna technology. Thus, the one or more processors 845 mayinclude digital signal processing capability to effectuate necessaryfunctions associated with reception and transmission of information viaantennas 809 ₁ to 809 _(N). Thus, the one or more processors 845 mayimplement a significant portion of the processing in communicationplatform 825.

Memory 855 can store data structures, code instructions, and specifycapabilities; code sequences for scrambling; spreading and pilottransmission, floor plan configuration, access point deployment andfrequency plans; and so on. In one example, computer instructions toimplement to synchronization flows shown in FIGS. 5A and/or 5B can beimplemented in memory 855.

Processor 845 can be coupled to the memory 855 in order to store andretrieve information necessary to operate and/or confer functionality tocommunication platform 825, network interface 835 (e.g., that coupledthe access point to core network devices such as but not limited to anetwork controller), and other operational components (e.g., multimodechipset(s), power supply source; not shown) that support the accesspoint 800. The access point 800 can further include an interface 865 forcommunication between the 5G and eNodeB. That interface may insteadutilize network interface 835. The access point may also includecomponent 875 to activate/deactivate SCell spectrum working inconjunction with 5G/eNodeB synchronization component 885 toactivate/deactivate SCell spectrum for use by the 5G RAT or the LTE RAT.In addition, it is to be noted that the various aspects disclosed in thesubject specification can also be implemented through (i) programmodules stored in a computer-readable storage medium or memory (e.g.,memory 855) and executed by a processor (e.g., processor 845), or (ii)other combination(s) of hardware and software, or hardware and firmware.

In the subject specification, terms such as “data store,” data storage,”“database,” “cache,” and substantially any other information storagecomponent relevant to operation and functionality of a component, referto any form of memory that can store information and be read bycomputers or processors. Memory may be volatile memory or nonvolatilememory, or both. Nonvolatile memory can include read only memory (ROM),programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable ROM (EEPROM), or flash memory. In additionnon-volatile memory can include magnetic and optical memory. Volatilememory can include random access memory (RAM), available in many formssuch as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM(SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM),Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM). Additionally,the disclosed memory components of systems or methods herein areintended to comprise, without being limited to comprising, these and anyother suitable types of memory.

While dynamic sharing of the spectrum has been described above, in otherembodiments, the different RATs share the spectrum on a more static orsemi-static basis by using duty cycles. For example, as shown in FIG. 9,where the LTE usage in the cell is high, 55% of the time the spectrum isallocated for LTE and 45% of the time the spectrum is allocated for 5G.Thus, e.g., out of for every X frames, where X is an integer, 55% of Xframes are reserved for LTE and the remaining 45% of X frames arereserved for 5G. The traffic statistics may be monitored and the dutycycle may be adjusted on any suitable time scale, e.g., every day, everyhour, every 10 minutes, every 10 seconds, or other appropriate timescale. Such an approach has the advantage of reducing signaling betweenthe eNodeB and the 5G base station regarding dynamic spectrum sharing.The UEs still have adjust to the switching between the 5G and LTE andthis can be done either by blind detection at the UE or via explicitsignaling from the network.

Thus, aspects of sharing spectrum between LTE and 5G radio accesstechnologies have been described. The description set forth herein isillustrative, and is not intended to limit the scope of the followingclaims. Variations and modifications of the embodiments disclosed hereinmay be made based on the description set forth herein, without departingfrom the scope of the following claims.

What is claimed is:
 1. A system comprising: a first base stationutilizing a first radio access technology to communicate with first userequipment, wherein the first base station uses a frequency spectrumduring a first time period; and a second base station utilizing a secondradio access technology to communicate with second user equipment,wherein the second base station uses a portion of the frequency spectrumduring a second time period, wherein the second base station isconfigured to send to the first base station a request that the firstbase station make the portion of the frequency spectrum available foruse during the first time period by the second base station, wherein thesecond user equipment is configured to determine that the portion of thefrequency spectrum is unavailable during the first time periodresponsive to a detected absence of one or more pilot tones in theportion of the frequency spectrum in the first time period.
 2. Thesystem of claim 1, wherein the portion of the frequency spectrumcomprises a second portion of the frequency spectrum, wherein the firstbase station uses a first portion of the frequency spectrum as a primarycell and uses the second portion of the frequency spectrum as asecondary cell aggregated with the primary cell during the first timeperiod.
 3. The system of claim 2, wherein the first base station and thesecond base station communicate regarding availability of the secondportion of the frequency spectrum via an interface between the firstbase station and the second base station.
 4. The system of claim 1,wherein the second user equipment does not perform measurementprocedures on the portion of the frequency spectrum responsive to thedetected absence of the one or more pilot tones in the portion of thefrequency spectrum, wherein the absence of the one or more pilot tonesis detected by the second user equipment after having detected apresence of pilot tones in the portion of the frequency spectrum.
 5. Thesystem of claim 4, wherein the second user equipment periodicallyperforms checking for the presence of pilot tones after detecting theabsence of the one or more pilot tones.
 6. The system of claim 5,wherein the second user equipment resumes performing the measurementprocedures on the portion of the frequency spectrum responsive todetecting the presence of pilot tones while performing the checking. 7.The system of claim 1, wherein the first base station performsdeactivating of the portion of the frequency spectrum responsive to therequest, and wherein the first base station signals the second basestation regarding the deactivating.
 8. The system of claim 1, whereinthe second base station signals the first base station regarding anavailability of the portion of the frequency spectrum for utilization bythe first base station.
 9. The system of claim 8, wherein the secondbase station deactivates subcarriers in a primary cell of the secondbase station in the portion of the frequency spectrum to make theportion of the frequency spectrum available for use by the first basestation.
 10. A method comprising: dynamically sharing, by a processingsystem including a processor and utilizing a first radio accesstechnology, a frequency spectrum with a second radio access technology,wherein a first base station utilizes the first radio access technologyto communicate with first user equipment, the first base station usingthe frequency spectrum during a first time period; and wherein a secondbase station utilizes a second radio access technology to communicatewith second user equipment, the second base station using a portion ofthe frequency spectrum during a second time period, wherein the secondbase station is configured to send to the first base station a requestthat the first base station make the portion of the frequency spectrumavailable for use during the first time period by the second basestation, wherein the second user equipment is configured to determinethat the portion of the frequency spectrum is unavailable during thefirst time period responsive to a detected absence of one or more pilottones in the portion of the frequency spectrum in the first time period.11. The method of claim 10, wherein the portion of the frequencyspectrum comprises a second portion of the frequency spectrum, whereinthe first base station uses a first portion of the frequency spectrum asa primary cell and uses the second portion of the frequency spectrum asa secondary cell aggregated with the primary cell during the first timeperiod.
 12. The method of claim 11, wherein the first base station andthe second base station communicate regarding availability of the secondportion of the frequency spectrum via an interface between the firstbase station and the second base station.
 13. The method of claim 10,wherein the second user equipment does not perform measurementprocedures on the portion of the frequency spectrum responsive to thedetected absence of the one or more pilot tones in the portion of thefrequency spectrum, wherein the absence of the one or more pilot tonesis detected by the second user equipment after having detected apresence of pilot tones in the portion of the frequency spectrum. 14.The method of claim 10, wherein the first base station performsdeactivating of the portion of the frequency spectrum responsive to therequest, and wherein the first base station signals the second basestation regarding the deactivating.
 15. The method of claim 10, whereinthe second base station signals the first base station regarding anavailability of the portion of the frequency spectrum for utilization bythe first base station.
 16. A device comprising: a processing systemincluding a processor; and a memory that stores executable instructionsthat, when executed by the processing system, facilitate performance ofoperations comprising: dynamically sharing, by a first radio accesstechnology, a frequency spectrum with a second radio access technology,wherein a first base station utilizes the first radio access technologyto communicate with first user equipment, the first base station usingthe frequency spectrum during a first time period; and wherein a secondbase station utilizes the second radio access technology to communicatewith second user equipment, the second base station using a portion ofthe frequency spectrum during a second time period, wherein the secondbase station is configured to send to the first base station a requestthat the first base station make the portion of the frequency spectrumavailable for use during the first time period by the second basestation, wherein the second user equipment is configured to determinethat the portion of the frequency spectrum is unavailable during thefirst time period responsive to a detected absence of one or more pilottones in the portion of the frequency spectrum in the first time period.17. The device of claim 16, wherein the portion of the frequencyspectrum comprises a second portion of the frequency spectrum, whereinthe first base station uses a first portion of the frequency spectrum asa primary cell and uses the second portion of the frequency spectrum asa secondary cell aggregated with the primary cell during the first timeperiod.
 18. The device of claim 17, wherein the first base station andthe second base station communicate regarding availability of the secondportion of the frequency spectrum via an interface between the firstbase station and the second base station.
 19. The device of claim 16,wherein the second user equipment does not perform measurementprocedures on the portion of the frequency spectrum responsive to thedetected absence of the one or more pilot tones in the portion of thefrequency spectrum, wherein the absence of the one or more pilot tonesis detected by the second user equipment after having detected apresence of pilot tones in the portion of the frequency spectrum. 20.The device of claim 19, wherein the second user equipment periodicallyperforms checking for the presence of pilot tones after detecting theabsence of the one or more pilot tones, and wherein the second userequipment resumes performing the measurement procedures on the portionof the frequency spectrum responsive to detecting the presence of pilottones while performing the checking.